Network transformers are used to deliver power to metropolitan areas and are typically housed in vaults located underground or at surface level. Network transformers receive power from a primary network which is the power source and deliver power through a secondary network to consumers. Network transformers are typically fluid-filled, utilizing a dielectric fluid to insulate the core and coil windings. When a fluid-filled network transformer ruptures due to a fault or other failure, the fluid may spread into heavily populated areas and pollute the environment. Accordingly, there is a need for a new type of network transformer that is insulated with a non-toxic material and stable against rupture. The present invention is directed to such a network transformer having a benign and non-volatile insulating medium.